Fort de Bertheaume

Fort de Bertheaume is a fortress on a rocky islet linked to the shore by a footbridge, positioned at the entrance to the Iroise Sea. The structure features multiple levels stacked upon each other showing different building techniques and remains accessible through a small bridge crossing.

Military engineer Vauban built this fortress in 1690 under orders from Louis XIV to defend the naval base at Brest against maritime attacks. The facility was later expanded with reinforced defenses to strengthen its protective role.

The fort takes its name from its original location and displays layered construction styles from different eras stacked together. Visitors can observe how each period left its own mark, from simple stonework to heavy gun emplacements built into the walls.

Access to the fortress is by a short bridge which may be restricted at high tide, so checking tidal times is wise. Guided tours are available during warmer months and most areas require good shoes for climbing and exploring.

The building served as a prison and detention site for political prisoners in the past, a lesser-known facet of its history. This secondary use reveals how the strategic location was employed for different purposes of authority.

Location: Plougonvelin

GPS coordinates: 48.33694,-4.69758

Latest update: December 8, 2025 19:47